Tensioning & Torquing

Need size? and its not about pump pressure after the grade selection.

B7 = proof strength = 105.000 lbf/in2, "size" is required for "dry torque" = "clamping force"

Of course it's about pump pressure. If the proper bolt load has been defined, he'll need to know how much hydraulic pressure to apply to the tensioner pump. Assuming that "tensioning" rather than "torquing" is indeed the method being used to apply the load, the first question is: how many tensioners will be used for simultaneous load application? If the entire flange is being loaded at once (100% tensioning) the calculation is fairly simple. When one goes below 50%, the calculation becomes more cumbersome. It all has to do with load relaxation. Once that factor has been determined, once simply divides the required preload by the tensioner area to determine the applied hydraulic pressure. If, for some reason, the question relates to "how to determine the pressure of a hydraulic torque wrench pump", everything is thrown out the window. For all of the accuracy of "torque", one might as well just beat'n'bash the darn bolts. "Torque" has dubious and limited relationship to bolt load. "Torque" is not and cannot be used to define how "tight" a fastener is. Whenever "torquing" can't be avoided on critical joints, the resultant bolt load MUST BE VERIFIED by measuring the stretch of the fasteners.